1. Field of the Invention
This invention relates to a connector for electric equipment and electric equipment having the connector, particularly to a shelled connector and electric equipment having a printed circuit board with the shelled connector secured thereto.
2. Description of the Related Art
A shelled connector secured on a printed circuit board has a metal shell encapsulating a contact housing. The metal shell is connected to an ground terminal on the printed circuit board to shell an electromagnetic or electrostatic noise from the external environment. Since practical connection of the metal shell with the ground terminal on the printed circuit board is usually carried out by using a metal fitting screwed down to the metal shell, an electric path many electric contacts between them is created. This tends to cause an increase in ground impedance due to instability in contact resistance.
As shown in FIG. 1, a conventional shelled connector 1 of a right-angle type, comprises an insulating body 1a, electric contacts 1b in a contact housing 1a-1 encapsulated by a metal shell 1d, and terminal pins 1c coupled to the respective contact. The terminal pins 1c are arranged perpendicularly to the direction to receive the counter cable plug connector (not shown) by insertion. The shelled connector 1 has a screw hole 1a--1a penetrating both the insulating body 1a and the metal shell 1d for securing the shelled connector to the chassis panel. The shelled connector 1 also has a through-hole 1a-1b, at both ends of the connector 1, in the L-shaped securing portion 1a-2 of the insulating body 1a for inserting the tip 1e-2 of the temporary metal tack 1e. The tip 1e-2 of the temporary metal tack 1e is tapered like shape of an arrow with a slit 1e-2a along the axis, which makes it easy to insert the tip 1e-2 into the narrow through-hole by elastic deformation and difficult to pull it out of the hole by a hooking action. FIG. 2 is a sectional view of the conventional shelled connector shown in FIG. 1 mounted on a metal chassis panel 3a of a metal cabinet 3 and a circuit board 2. The shelled connector 1 is mounted on a printed circuit board 2 by inserting terminal pins 1c into through-holes 2a for signals and also inserting the tip 1e-2 of the temporary metal tack 1e into a through-hole 2b-1 for a ground line and soldering each of them. The shelled connector 1 mounted on a printed circuit board 2 is secured to the metal chassis panel 3a of a metal cabinet 3 by inserting the contact housing 1a-1 into a trapezoidal shaped hole 3a-1 of the metal chassis panel 3a and also inserting a screw 4 into each screw hole in both outer sides of the trapezoidal shaped hole to fit in with the screw hole 1a-1a of the L-shaped securing portion 1a-2 of the insulating body 1a. Thus, the ground path by this structure is from the metal shell 1d to the through-hole 2b-1 for a ground line by way of the panel 3a, the screw 4, and the temporary metal tack 1e, successively. However, this structure of the ground line has so many contacts that an electric connection is apt to be instable and fails to provide a reliable ground contact. Therefore, it has been desired for a long time to provide a shelled connector having a stable and reliable ground contact to the circuit board.